Improvement in coiled springs for cars



A. FRENCH.

COILED SPRINGS FOR CARS.

Patented Apr118,1876.

No. 176,174,l

NRW

ILPETHS. PHOTO UNITED STATES PATENT OFFICE.

AARON FRENCH, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR 'TO A. FRENCH & CO., OF SAME PLACE.

` IMPROVEMENT IN COlLED SPRINGS FOR CARS.

Y Specification forming part of Letters Patent No. 176,174, dated April 18, 1876; application led February 26, 1876.

To all whom tt' may concern:

Be it known that I, AARON FRENCH, of Pittsburg, county ot' Allegheny, State ot' Pennsylvania, have invented or discovered a new and useful Improvement in Coiled Springs; and I do hereby declare the following to be a full, clear, concise, and exact description thereof, reference being had to the accompanying drawing, making a part of this specification, in which, like letters indicating like parts- Figure l is a longitudinal sectional view ot' one of my improved springs, and Fig. 2 is a perspective view thereof.

My improvement relates to the manufacture of coiled steel springs, wherein the spring, made of steel rods or bars, has its maximum size at or near the middle coil, and tapers therefrom each way to the bearing ends.

In the drawing', B represents one, and probably the best, form of my improved steel spring. It is made to shape from a round bar or rod, by rolling` or in other ot' the ways known to the art, and coiled by suitable machinery', so that the coil a, at or near the mid'- dle, shall be of' the maximum size desired in the spring. From the maximum coil the successive exterior coils b c d, &c., taper in regular succession, and lsuch taper is preferably made uniform along the length ot' the mate rial constituting the coils, to the outer bearing ends D D. The outermost or end coils are made with iat bearing-surfaces cl', such iiattened parts being made in the operation ot' shaping the rod or blank before coilin g.

This product gives a spring the ends of which are comparatively light, so thatthey will yield readily to the desired extent under a light blow or light weight, but so that the amount of compression under a heavy blow or weight, being distributed or divided between the two ends, will not be liable to result in the breakage of either end. At the same time, the ends being rst compressed, the

Iheavy middlev part will afford the necessary or desired elastic or yielding resistance to the heaviest Weight or blow. In this manner, also,

with the same weight of material, I am enabled to make a stron ger spring.

A coiled'spring made of a seven-eighth-inch diameter round, will have a certain strength, and give a certain maximum resistance. By my improvement I can take a steel rod of one inch diameter round, taper it from the middle each way, and get a spring of the same or a less amount ot material, but stronger, and capable of resisting a greater compressing force, or which, in other words, will act with an elastic operation under a greater load, as well as yield to the desired extent under aless load; and such springs I employ as buffer and draw-bar springs on railwaycars, and also as carrying-springs Linder earbodies, and for other analogous uses.

The taper described is preferably made unit'orm from the middle ot' the spring each way, and may be varied at pleasure in amount. I propose to make it in any ofthe known ways ot' making taper rounds, and do not limit myselt' in this respect.

For the purpose ot' making the taper, eccentric rolls having' each a half-round taper groove will be preferable. The rolling in such case is done from the middle or near the middle ofthe blank toward each end.

The same arrangement of taper may be applied in the making of coiled springs from rods or bars oval, elliptic, or rectangular in crosssection, the taper, however, being such that both the major and minor axes or transverse dimensions shall be reduced from the maximum at or near the middle to the outer ends. Such springs are, in practical use, arranged in nests, one inside the other, in the manner ordinarily practiced in the art.

I claim herein as my invention- A coiled spring made of steel rods or bars, tapered through the successive coils from the middle to each bearing end, substantially as set forth.

In testimony whereof I have hereunto set my hand.

AARON FRENCH.

Witnesses:

HARRY J. SCHLUTZ, GEORGE H. CHRISTY. 

